ActiveMQ Message Routing

There are several things to think about when you design the ActiveMQ message routing.

1) JMS Selectors. Selectors are a way of attaching a filter to a subscription to perform content based routing. Selectors are defined using SQL 92 syntax and typically apply to message headers; whether the standard properties available on a JMS message or custom headers you can add via the JMS code.

http://activemq.apache.org/selectors.html

ActiveMQ message properties and JMS message properties should be considered when using JMS selectors.

http://activemq.apache.org/activemq-message-properties.html

2) Wildcards. ActiveMQ supports destination wildcards to provide easy support for federated name hierarchies. A subscriber could use wildcards to define hierarchial pattern matches to the destinations to subscribe from. Note wildcards are not part of the JMS specification so are custom enhancements.

I think this feature is quite useful when some messages are only interesting to part of the consumers and relation structure is complex.

http://activemq.apache.org/wildcards.html

3) Advisory Message. It is kind of administrative information of ActiveMQ which helps to watch the system by subscribing to regular JMS messages. By default this is disabled.

http://activemq.apache.org/advisory-message.html?bcsi-ac-20A76BC15DBD50F6=1AADD8DD00000503CzAfPhVn8T+sJ2asth9iskWerAsTAgAAAwUAAJQ8hQIIBwAAVQAAAMKDAwA=

4) Message Redelivery. Messages are redelivered to a client when any of the following occurs:

1. A transacted session is used and rollback() is called.
2. A transacted session is closed before commit is called.
3. A session is using CLIENT_ACKNOWLEDGE and Session.recover() is called.

http://activemq.apache.org/message-redelivery-and-dlq-handling.html

(DLQ means dead letter queue)